The long-range purpose of this project is to study the function and structure of membrane ionic channels. The areas of present research are: 1) The permeability of organic cations in the sodium channel of Myxicola, 2) The influence of ionic strength on ionic selectivity, 3) The effects of neurotoxins on the axonal membrane in Myxicola, 4) The kinetics of various ions (mainly calcium, magnesium and cesium) through the sodium channels of the squid giant axon, 5) The influence of charge on ionic permeability in tissue-cultured cells derived from chick embryo muscles.